Multi-channel DC voltage and current acquisition circuit

Abstract

The utility model relates to the technical field of voltage and current acquisition, in particular to a multichannel direct-current voltage and current acquisition circuit, which comprises an MCU (Microprogrammed Control Unit) processing module and a plurality of current and voltage acquisition modules, and is characterized in that each current and voltage acquisition module comprises a voltage sampling unit, a current sampling unit, an analog-to-digital conversion unit, an analog front-end unit and an isolation unit, the voltage sampling unit and the current sampling unit are electrically connected with the analog front-end unit through a common end, the analog-to-digital conversion unit is electrically connected with the analog front-end unit and the isolation unit, and the isolation unit is electrically connected with the MCU processing module, so that electrical isolation between channels is realized, the anti-interference performance of simultaneous measurement of multiple channels is remarkably improved, and the measurement accuracy is improved. And crosstalk between channels is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of voltage and current acquisition, in particular to a multi-channel direct current voltage and current acquisition circuit. Background Art

[0002] In the fields of industrial control, power monitoring and scientific research, it is often necessary to monitor multiple voltage and current channels simultaneously. The existing technology has limitations in accuracy, synchronization, isolation performance, etc. and cannot meet high performance requirements. Most of the existing market products use round-robin acquisition, and the speed of multi-channel acquisition is slow. In addition, the multi-channel measurement adopted by the existing market products is a common ground method, there is no electrical isolation between channels, the anti-interference ability is poor, the measurement accuracy is not high, and the linear dynamic range is ideally small, which makes it impossible to meet the requirements of multi-channel high-speed measurement. Utility Model Content

[0003] The technical problem to be solved by the utility model is to provide a multi-channel DC voltage and current acquisition circuit capable of realizing high-precision synchronous acquisition.

[0004] In order to solve the above technical problems, the technical solution adopted by the utility model is:

[0005] A multi-channel DC voltage and current acquisition circuit comprises an MCU processing module and a plurality of current and voltage acquisition modules, each of the current and voltage acquisition modules comprises a voltage sampling unit, a current sampling unit, an analog-to-digital conversion unit, an analog front-end unit and an isolation unit, the voltage sampling unit and the current sampling unit are electrically connected to the analog front-end unit through a common terminal, the analog-to-digital conversion unit is electrically connected to the analog front-end unit and the isolation unit respectively, and the isolation unit is electrically connected to the MCU processing module.

[0006] Furthermore, the analog front-end unit includes an operational amplifier U2A, a non-phase input terminal of the operational amplifier U2A is electrically connected to the voltage sampling unit, an inverting input terminal of the operational amplifier U2A is electrically connected to the voltage sampling unit and the current sampling unit respectively, and an output terminal of the operational amplifier U2A is electrically connected to the analog-to-digital conversion unit.

[0007] Furthermore, the analog-to-digital conversion unit includes an ADC chip U4, the model of the ADC chip U4 is ADS127L01, the third pin of the ADC chip U4 is electrically connected to the analog front-end unit, the fourth pin of the ADC chip U4 is electrically connected to the eighth pin of the ADC chip U4 and the fourth pin of the ADC chip U4 and the eighth pin of the ADC chip U4 are both grounded, and the tenth pin, eleventh pin and twelfth pin of the ADC chip U4 are all electrically connected to the isolation unit.

[0008] Further, the isolation unit includes a photocoupler U1 and a photocoupler U5;

[0009] One end of the light source in the photoelectric coupler U1 is electrically connected to the analog-to-digital conversion unit, the other end of the light source in the photoelectric coupler U1 is grounded, one end of the light receiver in the photoelectric coupler U1 is connected to a power source, and the other end of the light receiver in the photoelectric coupler U1 is electrically connected to the MCU processing module;

[0010] One end of the light source in the photoelectric coupler U5 is electrically connected to the analog-to-digital conversion unit, the other end of the light source in the photoelectric coupler U5 is grounded, one end of the light receiver in the photoelectric coupler U5 is connected to the power supply, and the other end of the light receiver in the photoelectric coupler U5 is electrically connected to the MCU processing module.

[0011] Furthermore, the voltage sampling unit includes a resistor R1 and a resistor R2, one end of the resistor R1 is electrically connected to one end of the resistor R2 and the analog front end unit, and the other end of the resistor R2 is electrically connected to the current sampling unit and the analog front end unit.

[0012] Furthermore, the current sampling unit includes a resistor R13, one end of the resistor R13 is electrically connected to the current sampling unit and the analog front end unit respectively, and the other end of the resistor R13 is electrically connected to the analog front end unit.

[0013] Furthermore, the MCU processing module includes a chip U10, the model of the chip U10 is STM32F103VCTB, and the signal input end of the chip U10 is electrically connected to the isolation unit.

[0014] Furthermore, it also includes an isolation power supply module, and the isolation power supply module is electrically connected to the plurality of isolation units respectively.

[0015] Furthermore, it also includes a storage module, which is electrically connected to the MCU processing module.

[0016] Furthermore, it also includes a communication module, which is electrically connected to the MCU processing module.

[0017] The beneficial effects of the utility model are:

[0018] The present solution sets up several current and voltage acquisition modules, each of which includes a voltage sampling unit, a current sampling unit, an analog-to-digital conversion unit, an analog front-end unit and an isolation unit. The voltage sampling unit and the current sampling unit are electrically connected to the analog front-end unit through a common terminal, the analog-to-digital conversion unit is electrically connected to the analog front-end unit and the isolation unit respectively, the isolation unit is electrically connected to the MCU processing module, the voltage sampling unit is used to collect voltage information, the current sampling unit is used to collect current information, the analog front-end unit amplifies and filters the voltage signal collected by the voltage sampling unit and the current signal collected by the current sampling unit respectively, and then connects to the isolation unit, the isolation unit can ensure that several current and voltage acquisition modules (i.e., different channels) do not interfere with each other, the analog-to-digital conversion unit is used to convert the analog signal into a digital signal, and the MCU processing module is used to control the data acquisition of the analog-to-digital conversion unit; the present solution realizes electrical isolation between channels through the cooperation between the MCU processing module, the voltage sampling unit, the current sampling unit, the analog-to-digital conversion unit, the analog front-end unit and the isolation unit, significantly improves the anti-interference performance of simultaneous multi-channel measurement, and avoids crosstalk between channels. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a module connection block diagram of the multi-channel DC voltage and current acquisition circuit of the utility model;

[0020] Figure 2 It is a circuit schematic diagram of a current and voltage acquisition module of a multi-channel DC voltage and current acquisition circuit of the utility model;

[0021] Figure 3 It is a circuit schematic diagram of the MCU processing module of the multi-channel DC voltage and current acquisition circuit of the utility model;

[0022] Figure 4 It is a circuit schematic diagram of an isolated power supply module of a multi-channel DC voltage and current acquisition circuit of the utility model;

[0023] Description of labels:

[0024] 1. MCU processing module; 2. Current and voltage acquisition module; 201. Voltage sampling unit; 202. Current sampling unit; 203. Analog-to-digital conversion unit; 204. Analog front-end unit; 205. Isolation unit; 3. Isolation power supply module; 4. Storage module; 5. Communication module. DETAILED DESCRIPTION

[0025] In order to explain the technical content, achieved objectives and effects of the present invention in detail, the following is an explanation in conjunction with the implementation modes and the accompanying drawings.

[0026] Please refer to Figure 1 , the technical solution adopted by the utility model is:

[0027] A multi-channel DC voltage and current acquisition circuit comprises an MCU processing module and a plurality of current and voltage acquisition modules, each of the current and voltage acquisition modules comprises a voltage sampling unit, a current sampling unit, an analog-to-digital conversion unit, an analog front-end unit and an isolation unit, the voltage sampling unit and the current sampling unit are electrically connected to the analog front-end unit through a common terminal, the analog-to-digital conversion unit is electrically connected to the analog front-end unit and the isolation unit respectively, and the isolation unit is electrically connected to the MCU processing module.

[0028] From the above description, it can be seen that the beneficial effects of the utility model are:

[0029] The present solution sets up several current and voltage acquisition modules, each of which includes a voltage sampling unit, a current sampling unit, an analog-to-digital conversion unit, an analog front-end unit and an isolation unit. The voltage sampling unit and the current sampling unit are electrically connected to the analog front-end unit through a common terminal, the analog-to-digital conversion unit is electrically connected to the analog front-end unit and the isolation unit respectively, the isolation unit is electrically connected to the MCU processing module, the voltage sampling unit is used to collect voltage information, the current sampling unit is used to collect current information, the analog front-end unit amplifies and filters the voltage signal collected by the voltage sampling unit and the current signal collected by the current sampling unit respectively, and then connects to the isolation unit, the isolation unit can ensure that several current and voltage acquisition modules (i.e., different channels) do not interfere with each other, the analog-to-digital conversion unit is used to convert the analog signal into a digital signal, and the MCU processing module is used to control the data acquisition of the analog-to-digital conversion unit; the present solution realizes electrical isolation between channels through the cooperation between the MCU processing module, the voltage sampling unit, the current sampling unit, the analog-to-digital conversion unit, the analog front-end unit and the isolation unit, significantly improves the anti-interference performance of simultaneous multi-channel measurement, and avoids crosstalk between channels.

[0030] Furthermore, the analog front-end unit includes an operational amplifier U2A, a non-phase input terminal of the operational amplifier U2A is electrically connected to the voltage sampling unit, an inverting input terminal of the operational amplifier U2A is electrically connected to the voltage sampling unit and the current sampling unit respectively, and an output terminal of the operational amplifier U2A is electrically connected to the analog-to-digital conversion unit.

[0031] It can be seen from the above description that the operational amplifier U2A can buffer and amplify the input voltage signal and current signal.

[0032] Furthermore, the analog-to-digital conversion unit includes an ADC chip U4, the model of the ADC chip U4 is ADS127L01, the third pin of the ADC chip U4 is electrically connected to the analog front-end unit, the fourth pin of the ADC chip U4 is electrically connected to the eighth pin of the ADC chip U4 and the fourth pin of the ADC chip U4 and the eighth pin of the ADC chip U4 are both grounded, and the tenth pin, eleventh pin and twelfth pin of the ADC chip U4 are all electrically connected to the isolation unit.

[0033] From the above description, we can know that the ADC chip model ADS127L01 is a 24-bit high-precision, high-speed sampling ADC chip that converts analog signals into digital signals; the ADC chips of all channels work synchronously through the same clock source, which can ensure the synchronization of data sampling.

[0034] Further, the isolation unit includes a photocoupler U1 and a photocoupler U5;

[0035] One end of the light source in the photoelectric coupler U1 is electrically connected to the analog-to-digital conversion unit, the other end of the light source in the photoelectric coupler U1 is grounded, one end of the light receiver in the photoelectric coupler U1 is connected to a power source, and the other end of the light receiver in the photoelectric coupler U1 is electrically connected to the MCU processing module;

[0036] One end of the light source in the photoelectric coupler U5 is electrically connected to the analog-to-digital conversion unit, the other end of the light source in the photoelectric coupler U5 is grounded, one end of the light receiver in the photoelectric coupler U5 is connected to the power supply, and the other end of the light receiver in the photoelectric coupler U5 is electrically connected to the MCU processing module.

[0037] It can be seen from the above description that the photocoupler U1 and the photocoupler U5 are used to provide photoelectric isolation to isolate the influence of high voltage and noise.

[0038] Furthermore, the voltage sampling unit includes a resistor R1 and a resistor R2, one end of the resistor R1 is electrically connected to one end of the resistor R2 and the analog front end unit, and the other end of the resistor R2 is electrically connected to the current sampling unit and the analog front end unit.

[0039] It can be seen from the above description that the resistor R1 and the resistor R2 divide the input voltage.

[0040] Furthermore, the current sampling unit includes a resistor R13, one end of the resistor R13 is electrically connected to the current sampling unit and the analog front end unit respectively, and the other end of the resistor R13 is electrically connected to the analog front end unit.

[0041] It can be seen from the above description that the current signal is converted into a voltage signal by the resistor R13 and then transmitted to the analog front end unit for processing.

[0042] Furthermore, the MCU processing module includes a chip U10, the model of the chip U10 is STM32F103VCT6, and the signal input end of the chip U10 is electrically connected to the isolation unit.

[0043] Furthermore, it also includes an isolation power supply module, and the isolation power supply module is electrically connected to the plurality of isolation units respectively.

[0044] It can be seen from the above description that by providing an isolated power supply module, each channel can work independently.

[0045] Furthermore, it also includes a storage module, which is electrically connected to the MCU processing module.

[0046] It can be seen from the above description that the storage module is used to store calibration parameters and temporary data.

[0047] Furthermore, it also includes a communication module, which is electrically connected to the MCU processing module.

[0048] Please refer to Figures 1 to 4 , Embodiment 1 of the present utility model is:

[0049] Please refer to Figure 1 A multi-channel DC voltage and current acquisition circuit includes an MCU processing module 1 and a plurality of current and voltage acquisition modules 2 (the number of the current and voltage acquisition modules 2 in this embodiment is 24), each of the current and voltage acquisition modules 2 includes a voltage sampling unit 201, a current sampling unit 202, an analog-to-digital conversion unit 203, an analog front-end unit 204 and an isolation unit 205, the voltage sampling unit 201 and the current sampling unit 202 are electrically connected to the analog front-end unit 204 through a common terminal, the analog-to-digital conversion unit 203 is electrically connected to the analog front-end unit 204 and the isolation unit 205 respectively, and the isolation unit 205 is electrically connected to the MCU processing module 1.

[0050] Please refer to Figure 2 The analog front-end unit 204 includes an operational amplifier U2A, a non-inverting input terminal of the operational amplifier U2A is electrically connected to the voltage sampling unit 201, an inverting input terminal of the operational amplifier U2A is electrically connected to the voltage sampling unit 201 and the current sampling unit 202 respectively, and an output terminal of the operational amplifier U2A is electrically connected to the analog-to-digital conversion unit 203.

[0051] The analog front end unit 204 further includes a resistor R3 (whose resistance value ranges from 0.01Ω to 10kΩ) and a capacitor C4 (whose capacitance value ranges from 10pF to 100μF). For the specific connection relationship between the resistor R3 and the capacitor C4 and the components, please refer to Figure 2 ;

[0052] Please refer to Figure 2 The analog-to-digital conversion unit 203 includes an ADC chip U4, the model of the ADC chip U4 is ADS127L01, the third pin of the ADC chip U4 is electrically connected to the analog front-end unit 204, the fourth pin of the ADC chip U4 is electrically connected to the eighth pin of the ADC chip U4, and the fourth pin of the ADC chip U4 and the eighth pin of the ADC chip U4 are both grounded, and the tenth pin, the eleventh pin and the twelfth pin of the ADC chip U4 are all electrically connected to the isolation unit 205.

[0053] The analog-to-digital conversion unit 203 further includes a capacitor C5 (whose capacitance value ranges from 10pF to 100μF) and a resistor R4 (whose resistance value ranges from 10Ω to 1MΩ). For the specific connection relationship between the capacitor C5 and the resistor R4 and the components, please refer to Figure 2 ;

[0054] Please refer to Figure 2 , the isolation unit 205 includes a photocoupler U1 (model HCPL-817) and a photocoupler U5 (model HCPL-817);

[0055] One end of the light source in the photoelectric coupler U1 is electrically connected to the analog-to-digital conversion unit 203, the other end of the light source in the photoelectric coupler U1 is grounded, one end of the light receiver in the photoelectric coupler U1 is connected to a power source, and the other end of the light receiver in the photoelectric coupler U1 is electrically connected to the MCU processing module 1;

[0056] One end of the light source in the photoelectric coupler U5 is electrically connected to the analog-to-digital conversion unit 203, the other end of the light source in the photoelectric coupler U5 is grounded, one end of the light receiver in the photoelectric coupler U5 is connected to the power supply, and the other end of the light receiver in the photoelectric coupler U5 is electrically connected to the MCU processing module 1.

[0057] The isolation unit 205 further includes a resistor R8 (whose resistance value ranges from 1Ω to 1MΩ). For the specific connection relationship between the resistor R8 and various components, please refer to Figure 2 ;

[0058] Please refer to Figure 2 The voltage sampling unit 201 includes a resistor R1 (a voltage dividing resistor with a resistance value ranging from 1 kΩ to 10 MΩ) and a resistor R2 (a voltage sampling resistor with a resistance value ranging from 1 kΩ to 10 MΩ), one end of the resistor R1 is electrically connected to one end of the resistor R2 and the analog front end unit 204, and the other end of the resistor R2 is electrically connected to the current sampling unit and the analog front end unit 204.

[0059] Please refer to Figure 2The current sampling unit 202 includes a resistor R13 (resistance value is 0.01Ω), one end of the resistor R13 is electrically connected to the current sampling unit 202 and the analog front end unit 204 respectively, and the other end of the resistor R13 is electrically connected to the analog front end unit 204.

[0060] The MCU processing module 1 includes a chip U10, the model of the chip U10 is STM32F103VCT6, the signal input end of the chip U10 is electrically connected to the isolation unit 205, and the MCU processing module 1 also includes chip peripheral devices, please refer to Figure 3 .

[0061] Please refer to Figure 1 , and also includes an isolated power supply module 3, which is electrically connected to the plurality of isolation units 205 respectively.

[0062] Please refer to Figure 4 The isolated power supply module 3 includes a capacitor C1, a resistor R6, a capacitor C7, a chip U3, an inductor L1, a resistor R7, a capacitor C6, a resistor R5, a resistor R9, a capacitor C2, a capacitor C3, a resistor R11, a resistor R12, a capacitor C10, a resistor R17, a chip U8 and a capacitor C11. For the specific connection relationship between the components, please refer to Figure 3 ;

[0063] Capacitor C1 is used for power supply voltage stabilization and de-jittering, and its value range is 10nF~1000μF;

[0064] Resistor R6 is used to enable pull-up, and its value range is 0Ω~1Ω;

[0065] Capacitor C7 is used for de-jittering and voltage stabilization, and its value range is 10nF~10μF;

[0066] Chip U3 is a step-down DCDC chip, the model may be TLV62130RGT, or other step-down DCDC chips with the same function;

[0067] Inductor L1 is used for energy storage and continuous current in voltage reduction, and its value range is 1nH~10μH;

[0068] Resistor R7 is used for feedback channel, and its value range is 0Ω~10kΩ;

[0069] Resistors R5 and R9 are used for voltage divider feedback, with a value range of 1Ω to 100kΩ;

[0070] Capacitor C6 is used for de-jittering and voltage stabilization, and its value range is 10pF~10μF;

[0071] Capacitors C2 and C3 are used for voltage stabilization and de-jittering, with a value range of 0F to 1000μF;

[0072] Resistors R11 and R12 are used for voltage division, and their value range is 1Ω~1MΩ;

[0073] Capacitors C10 and C11 are used for voltage stabilization and de-jittering, and their value range is 10nF to 1000μF;

[0074] Resistor R17 is an enable pull-up resistor with a value range of 0Ω to 1MΩ;

[0075] Chip U8 is a linear voltage regulator chip, the model can be REF5050 or other LDO chips with the same function;

[0076] Please refer to Figure 1 , and also includes a storage module 4, which is electrically connected to the MCU processing module 1, and the storage module 4 uses a non-volatile memory (such as EEPROM\FLASH) to store calibration parameters and temporary data.

[0077] Please refer to Figure 1 , also includes a communication module 5, the communication module 5 is electrically connected to the MCU processing module 1, the communication module 5 is used for communication between the MCU processing module 1 and the external user interface, and can be an RS232 or RS485 communication controller, used to transmit the voltage and current data of each channel collected by the MCU processing module 1 to the external user interface.

[0078] The working principle of the above multi-channel DC voltage and current acquisition circuit is:

[0079] After the current signal is converted into a voltage signal by resistor R13, it is transmitted to the operational amplifier U2A for processing; the operational amplifier U2A amplifies the voltage signal collected by the voltage sampling unit 201 and the current signal collected by the current sampling unit 202, respectively, and filters them and connects them to the ADC chip; the analog front-end unit 204 includes a high-precision operational amplifier U2A (such as the OPAx277 series) to buffer and amplify the input voltage signal, and a passive RC low-pass filter (composed of resistor R3 and capacitor C4) to denoise the amplified signal and filter out high-frequency components that exceed the sampling requirements; the ADC chip model ADS127L01 is a 24-bit high-precision, high-speed sampling ADC chip that converts analog signals into digital signals; the ADC chips of all channels work synchronously through the same clock source to ensure the synchronization of data sampling; one end of the isolation power supply module 3 is connected to the power input end, and the other end is electrically connected to the MCU processing module 1 and the electrical The isolation unit 205 of the current and voltage acquisition module 2 and the reference voltage source (i.e., chip U8) in the isolation power supply module 3 use a high-stability reference voltage source (e.g., REF5050) to provide a reference voltage for the ADC chip to ensure conversion accuracy; the photocoupler U1 and the photocoupler U5 (e.g., a photocoupler of model HCPL-817) provide photoelectric isolation between the analog front-end and the back-end digital logic circuits to isolate the influence of high voltage and noise; and the isolation power supply module 3 provides an isolated power supply for the ADC chip U4 to achieve mutual isolation of the working power supplies of the 24-channel current and voltage acquisition modules 2; the MCU processing module 1 uses a microcontroller (e.g., STM32 series) to control the data acquisition of the ADC chip U4, processes the collected digital signals, denoises the collected data through the digital filter built into the microcontroller, and communicates with external devices through a serial communication interface (e.g., I2C\SPI\RS232\RS485).

[0080] The multi-channel DC voltage and current acquisition circuit designed in this scheme adopts a 24-bit high-precision, high-speed sampling ADC chip with high measurement accuracy. It ensures the accuracy of the measurement results through a stable reference voltage and a precision shunt resistor (i.e., resistor R13). The use of a passive RC low-pass filter (composed of resistor R3 and capacitor C4) further improves the signal-to-noise ratio of the signal and reduces the influence of noise on the signal accuracy. It can replace high-precision voltage, current and power meters to realize the function of synchronous sampling and measurement of multiple meters. Through the design of isolation unit and isolation power supply module, each channel can work independently, realizing electrical isolation between channels, significantly improving the anti-interference of simultaneous multi-channel measurement, and avoiding crosstalk between channels.

[0081] In summary, the utility model provides a multi-channel DC voltage and current acquisition circuit, by setting a plurality of current and voltage acquisition modules, each current and voltage acquisition module includes a voltage sampling unit, a current sampling unit, an analog-to-digital conversion unit, an analog front-end unit and an isolation unit, the voltage sampling unit and the current sampling unit are electrically connected to the analog front-end unit through a common terminal, the analog-to-digital conversion unit is electrically connected to the analog front-end unit and the isolation unit respectively, the isolation unit is electrically connected to the MCU processing module, the voltage sampling unit is used to collect voltage information, the current sampling unit is used to collect current information, the analog front-end unit is used to collect voltage information, and the voltage sampling unit is used to collect current information. The collected voltage signal and the current signal collected by the current sampling unit are amplified and filtered and then connected to the isolation unit. The isolation unit can ensure that several current and voltage acquisition modules (i.e., different channels) do not interfere with each other. The analog-to-digital conversion unit is used to convert analog signals into digital signals, and the MCU processing module is used to control the data acquisition of the analog-to-digital conversion unit. This solution achieves electrical isolation between channels through the cooperation between the MCU processing module, the voltage sampling unit, the current sampling unit, the analog-to-digital conversion unit, the analog front-end unit and the isolation unit, significantly improves the anti-interference performance of simultaneous multi-channel measurement, and avoids crosstalk between channels.

[0082] The above description is only an embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent transformations made using the contents of the specification and drawings of the present invention, or directly or indirectly applied in the relevant technical field, are also included in the patent protection scope of the present invention.

Claims

1. A multi-channel DC voltage and current acquisition circuit, characterized in that: It includes an MCU processing module and several current and voltage acquisition modules, each of which includes a voltage sampling unit, a current sampling unit, an analog-to-digital conversion unit, an analog front-end unit and an isolation unit. The voltage sampling unit and the current sampling unit are electrically connected to the analog front-end unit through a common terminal, the analog-to-digital conversion unit is electrically connected to the analog front-end unit and the isolation unit respectively, and the isolation unit is electrically connected to the MCU processing module.

2. The multi-channel DC voltage and current acquisition circuit according to claim 1, characterized in that: The analog front-end unit includes an operational amplifier U2A, a non-inverting input terminal of the operational amplifier U2A is electrically connected to a voltage sampling unit, an inverting input terminal of the operational amplifier U2A is electrically connected to a voltage sampling unit and a current sampling unit, respectively, and an output terminal of the operational amplifier U2A is electrically connected to an analog-to-digital conversion unit.

3. The multi-channel DC voltage and current acquisition circuit according to claim 1, characterized in that: The analog-to-digital conversion unit includes an ADC chip U4, the model of the ADC chip U4 is ADS127L01, the third pin of the ADC chip U4 is electrically connected to the analog front-end unit, the fourth pin of the ADC chip U4 is electrically connected to the eighth pin of the ADC chip U4, and the fourth pin of the ADC chip U4 and the eighth pin of the ADC chip U4 are both grounded, and the tenth pin, eleventh pin and twelfth pin of the ADC chip U4 are all electrically connected to the isolation unit.

4. The multi-channel DC voltage and current acquisition circuit according to claim 1, characterized in that: The isolation unit includes a photocoupler U1 and a photocoupler U5; One end of the light source in the photoelectric coupler U1 is electrically connected to the analog-to-digital conversion unit, the other end of the light source in the photoelectric coupler U1 is grounded, one end of the light receiver in the photoelectric coupler U1 is connected to a power source, and the other end of the light receiver in the photoelectric coupler U1 is electrically connected to the MCU processing module; One end of the light source in the photoelectric coupler U5 is electrically connected to the analog-to-digital conversion unit, the other end of the light source in the photoelectric coupler U5 is grounded, one end of the light receiver in the photoelectric coupler U5 is connected to the power supply, and the other end of the light receiver in the photoelectric coupler U5 is electrically connected to the MCU processing module.

5. The multi-channel DC voltage and current acquisition circuit according to claim 1, characterized in that: The voltage sampling unit includes a resistor R1 and a resistor R2, one end of the resistor R1 is electrically connected to one end of the resistor R2 and the analog front end unit, and the other end of the resistor R2 is electrically connected to the current sampling unit and the analog front end unit.

6. The multi-channel DC voltage and current acquisition circuit according to claim 1, characterized in that: The current sampling unit includes a resistor R13, one end of the resistor R13 is electrically connected to the current sampling unit and the analog front end unit respectively, and the other end of the resistor R13 is electrically connected to the analog front end unit.

7. The multi-channel DC voltage and current acquisition circuit according to claim 1, characterized in that: The MCU processing module includes a chip U10, the model of the chip U10 is STM32F103VCT6, and the signal input end of the chip U10 is electrically connected to the isolation unit.

8. The multi-channel DC voltage and current acquisition circuit according to claim 1, characterized in that: It also includes an isolated power supply module, which is electrically connected to the plurality of isolation units respectively.

9. The multi-channel DC voltage and current acquisition circuit according to claim 1, characterized in that: It also includes a storage module, which is electrically connected to the MCU processing module.

10. The multi-channel DC voltage and current acquisition circuit according to claim 1, characterized in that: It also includes a communication module, which is electrically connected to the MCU processing module.

Images